The staling of bread is an important issue in the baking industry because it imposes sharp limitations on the shelf life of bread products. To mitigate the impact of staling, special storage and packaging of bread is typically employed, which is costly and can be unattractive to the consumer. Such measures provide moderate improvement in shelf life, but even under optimal storage conditions, such as sealing the bread in a high humidity environment, most bread will begin to stale after only a few days. Improved packaging cannot eliminate staling.
Further, special packaging is not possible for the segment of the industry that desires to offer unpackaged products, including, for example, smaller bakeries which market “fresh baked” products, donut shops which offer their products on racks or the like, as well as retail grocery stores which are increasingly exploiting the market for unpackaged baked goods, such as bread loafs, muffins, bagels, donuts, and cookies. Often, the shelf life of unpackaged bread products is measured in hours and the entire inventory must be discarded and replaced with fresh product one or more times throughout the day. The value of discarded bread products in the United States exceeds $1 billion annually. Therefore, preventing or slowing the staling of bread products will provide a significant economic advantage.
Staling is a complex process involving numerous chemical and physical changes in the bread which have deleterious effects on the taste, texture, aroma, crumb structure, and mouthfeel of the product. While several models have been proposed to explain staling, it may be generally said to arise as a result of starch retrogradation, water loss from the bread, and water migration within the bread.
Water provides the moist mouthfeel characteristic of fresh bread and the loss of even small amounts of water, on the order of 1 or 2 percent, through evaporation has a pronounced negative impact on bread quality and shelf life. Staling may occur even in the absence of net water loss, not only due to starch retrogradation, but also as a result of water migration within the bread. Bread comprises numerous components, such as starch, sugar, fiber, and protein, each of which has a certain affinity for water. In freshly prepared bread, an initial equilibrium condition is established between the available water and each of these components, based in part on their relative binding energies with water molecules. During storage, the equilibrium is perturbed by water loss from the bread and chemical and physical changes within the bread. For example, starch retrogradation profoundly alters the moisture equilibrium, as free water will migrate to the crystalline domains of retrograded starch, where it is tightly held and unavailable to other bread components. Consequently, the starch-gluten network becomes more rigid as less free water is available to act as a plasticizer, resulting in a firmer, less soft crumb.
It is generally not possible to increase the moisture content of bread simply by adding more water to the dough because the dough becomes sticky and unworkable.
Glycerine, also called glycerin or glycerol, is a sweet, colorless, syrupy liquid which is miscible with water. It is generally known to include glycerine in baked goods to improve flavor, texture, color and to increase moistness. See Leffingwell, Georgia and Lesser, Milton A., “Glycerine in Modern Baking Practice,” The Bakers Digest, Vol. XIV, No. 12, June 1940, pp. 228-229, the disclosure of which is hereby incorporated by reference. Leffingwell and Lesser state that “the most important property of glycerine, however, is its natural hygroscopicity, and through this ability to retain and attract moisture is widely employed to maintain the essential freshness of breads and cakes.”
In conventional practice, glycerine is incorporated in baked goods at the bowl stage, by which is meant the stage of the dough making process where the solid ingredients are charged into a mixing bowl and water, along with other liquid ingredients, is added. Thus, a precise amount of liquid glycerine must be weighed and transferred to the bowl, a process made difficult or inconvenient by its sticky nature. It is generally preferred in the baking industry, particularly for production on a commercial scale, to handle dry as opposed to liquid ingredients. However, at present, there is not believed to exist a more convenient method of delivering glycerine in the dough making process. What are lacking are compositions for handling, transporting, storing, and using glycerine in a convenient dry, solid form.
The foregoing discussion is presented solely to provide a better understanding of nature of the problem confronting the art and should not be construed in any way as an admission as to prior art nor should the citation of any reference herein be construed as an admission that such reference constitutes “prior art” to the instant application.